Apparatus and method employing an annular device for intermediating between a winding mandrel and core

ABSTRACT

Cores can be engaged and disengaged with a plurality of annular devices fitted over a mandrel. The mandrel has fluid passage communicating with a spaced plurality of radially disposed channels. Pistons in the channels can, in response to fluid pressure, extend outwardly in order to bear on the annular devices. Changes in the volume of fluid inside the fluid passage and the channels are substantially equal to the total displacement of the pistons. Each annular device has an inner ring with at least one camming track rotatably mounted inside an outer ring. The inner ring has an inside portion including a material different from material of said outer ring. The outer ring is fitted inside the core and the inner ring is fitted over the mandrel. A gripping member is fitted in an aperture of the outer ring to move along the camming track. This gripping member is outwardly thrustable through the aperture in accordance with the position of the gripping member in the camming track.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to winding mandrels, and in particular, to winding with a controlled amount of slippage between the mandrel and winding cores.

[0003] 2. Description of Related Art

[0004] Sheet material made of paper, plastic or other materials is manufactured in a web that is wound into a relatively large roll. In many instances, this roll is too large for use in other manufacturing processes. For that reason, the web is often unwound and rewound into smaller rolls. In some cases, the web is slit into a plurality of webs that are then simultaneously wound into a number of axially shorter rolls.

[0005] The web is often rewound on an open cylindrical core that is mounted on a driving mandrel. In some cases the cores are locked into a fixed position on the mandrel, but often these cores are allowed to slip. This slippage can be designed to modulate the torque and therefore the tension of the rewinding web. When slippage is contemplated it must be carefully controlled so that the finished product is uniform. Therefore much care has been taken to control the slipping surfaces and the friction between them.

[0006] A known mandrel has slots that carry axially repositionable buttons that can be thrust radially outward to bear on the inside surface of a core. These buttons can be lifted by an underlying bar that is driven by an inflatable bladder contained in the hollow center of a mandrel. A disadvantage with this arrangement is that the friction between the buttons and the inside surface of the cores is variable. This variability is inevitable since the core material will change from job to job.

[0007] Other disadvantages arise from the use of the bladder. In order to prevent premature wear or leaking of the bladder, it must be made of a relatively tough material. On the other hand, significant amount of work must be done to inflate the bladder itself, which reduces the efficiency of the energy transferred to the buttons. Essentially, work is done increasing the volume of fluid inside the bladder, but this fluid increases much greater than would be needed simply to propel the buttons. Moreover, the bladder itself tends to have a somewhat limited service life, thus introducing disadvantageous maintenance requirements.

[0008] Another disadvantage with the bladder design is the difficulty in accurately controlling the friction and therefore the output torque produced by inflating the bladder. Essentially, the bladder has different modes of operation.

[0009] When initially inflated slightly, the bladder bears primarily on the button mechanism without contacting the inner wall of the mandrel. As pressure increases, the bladder engages the inside surface of the mandrel as well as the button mechanism and will deform appropriately to conform to these surfaces.

[0010] Because of the complexity of the interactions in the different modes, the output torque will not be linearly related to bladder pressure. This makes accurately controlling output torque more difficult.

[0011] In U.S. Pat. No. 4,220,291 an inflatable bladder can outwardly thrust balls to engage winding cores. The axial position of these balls is not adjustable.

[0012] Furthermore, if the cores are allowed to slip, their slippage will be determined in part by the friction between the cores and the balls. Also, these balls constitute a relatively small surface area that is subject to rapid wear and therefore high variability. See also U.S. Pat. No. 4,135,677 (air shaft with a pair of expandable sleeves surrounding an internal bladder); and U.S. Pat. No. 4,461,430 (differential winding air shaft). For appurtenant devices see U.S. Pat. No. 4,211,135 (cutting devices); U.S. Pat. No. 5,161,747 (pressing rollers); and U.S. Pat. No. 5,161,899 (bearing assembly allowing exchangeable support of shafts). For non-mandrel winding devices see U.S. Pat. No. 5,156,352.

[0013] In FIG. 11 of U.S. Pat. No. 4,431,142 an inflatable bladder drives steel spheres 52 against the inside of a collar 51. Rotation of collar 51 in one direction drives locking balls 49 up a ramp to lock against the inside of a core. Reverse rotation releases the core. Frictional slipping is expected between the inside surface of collar 51 and the steel spheres 52. This represents almost a point contact that will be greatly affected by wear.

[0014] In U.S. Pat. No. 5,279,470 a winding shaft is coupled to a number of winding rings, each ring having a number of spring biased segments. For example in FIG. 6 segments 2 have spring biased balls 10′, but these are only centering devices acting to the side of the winding cores 9.

[0015] In U.S. Pat. No. 4,964,586 an eccentric shaft can radially thrust elements against the inside of a winding core. Relative rotation of the eccentric shaft with respect to the thrust elements is normally prevented by a brake mechanism, but this braking force can be overcome by certain locking devices. The support strength of this arrangement is compromised by reliance on a relatively small, internal eccentric shaft. See also U.S. Pat. No. 4,893,765.

[0016] In U.S. Pat. No. 4,165,050 a plug with camming surfaces can be pressed axially inward to lift cam followers, which may be either cylindrical or spherical. When lifted, cam followers distend resilient ring 22 to clamp onto the inside of reel 34 of a tape cassette. This reference requires manual access at the axis of rotation and would be inappropriate for securing multiple winding cores on a large mandrel. See also U.S. Pat. No. 4,000,866 (disks brought together to expand an elastomeric ring and grip the reels of a videocassette).

[0017] In U.S. Pat. No. 4,763,850 a mechanism employing axially shifting members and rotating links can outwardly thrust gripping members against the inside surface of a yarn bobbin or holder. This arrangement employs a relatively large number of moving components that compromise its reliability.

[0018] In FIG. 3 of U.S. Pat. No. 4,635,871 a rod inside a hollow mandrel can be axially shifted to either extend or retract lugs in order to engage or release a core that may be placed on the mandrel. These lugs are rotated so a corner of the lug bears against the core. This presents a relatively small surface area that would wear rapidly in the presence of core slippage.

[0019] In U.S. Pat. No. 4,21 3,577 separate pressure lines are provided to opposite sides of a hydraulic piston to (a) extend the piston before and while sheet metal is coiled onto the mandrel, and (b) retract the piston when the coil is to be removed. The mandrel is notched to receive one end of the sheet metal strip. Thus, this reference is unconcerned with winding strips onto a separate core and for permitting slippage between the mandrel and core.

[0020] In Figure III of U.S. Pat. No. 4,147,312 hydraulic pressure applied through a hollow mandrel distends diaphragms to press buttons against the inside surface of a core. The buttons are not directly operated by hydraulic pressure, but are operated indirectly through diaphragms.

[0021] In U.S. Pat. No. 4,352,470 four segments 27 can be driven axially up an inclined surface on a mandrel to be thrust outwardly. This mandrel telescopically contracts to alter its length and its utility would therefore be greatly restricted. See also U.S. Pat. No. 5,314,135 (tapered inner tube outwardly thrusts a slotted outer tube against the inner surface of a core); U.S. Pat. No. 5,683,057 (inclined surfaces of retractable collar drives lugs 26 outwardly to clamp to the inside of a core); and U.S. Pat. No. 4,079,896 (shoes driven up a conical surface in a chuck to bear against the inside surface of a core).

[0022] See also U.S. Pat. No. 5,533,691 (hub presses cores axially not radially); U.S. Pat. No. 4,436,249 (mandrel with latch that locks onto a spool); and U.S. Pat. No. 4,325,522 (brake for a cable spool). For other winding machines see U.S. Pat. No. 4,770,360.

SUMMARY OF THE INVENTION

[0023] In accordance with the illustrative embodiments demonstrating features and advantages of the present invention, there is provided an annular device for intermediating force transfer between a winding mandrel and a core onto which a web is to be wound. The annular device has an inner ring with at least one camming track rotatably mounted inside an outer ring. The inner ring has an inside portion comprising a material different from material of said outer ring. The outer ring is adapted to be fitted inside the core and the inner ring is adapted to be fitted over the mandrel. Also included is a gripping member fitted in an aperture of the outer ring to move along the camming track. This gripping member is outwardly thrustable through the aperture in accordance with the position of the gripping member in the camming track.

[0024] In accordance with another aspect of the invention a web winding assembly is provided that can engage and disengage cores with a plurality of annular devices. The assembly has a mandrel with a spaced plurality of radially disposed channels. The mandrel has a fluid passage communicating with the channels. Also included is a plurality of pistons mounted to reciprocate in different corresponding ones of the channels. The pistons are operable in response to fluid pressure in the channels to extend out of the mandrel in order to bear on the annular devices. Changes in the volume of fluid inside the fluid passage and the channels are substantially equal to the total displacement of the pistons.

[0025] In accordance with yet another aspect of the invention a web winding method is provided which employs annular devices located on a mandrel fitted with core engaging pistons. The method includes the steps of loading the cores over the annular devices. Another step is outwardly driving the pistons with directly applied fluid pressure in order to frictionally engage the annular devices with said pistons. Changes in the volume of fluid inside the mandrel being substantially equal to the total displacement of the pistons. The method also includes the step of locking the cores onto the annular devices. Another step is rotating the mandrel to wind the web, while allowing slippage predominantly between the annular device and the mandrel, in order to avoid slippage predominantly influenced by interface attributes between the cores and the annular devices. The method also includes the step of unlocking and removing the cores from the annular devices.

[0026] In accordance with still yet another aspect of the invention an annular device can intermediate force transfer between a winding mandrel and a core onto which a web is to be wound. The annular device includes an outer ring having at least one aperture and adapted to be fitted inside the core. Also included is a gripping member fitted in the aperture of the outer ring. The annular device also includes an inner ring rotatably mounted inside the outer ring and adapted to be fitted over the mandrel. The inner ring has at least one camming track for receiving and allowing movement of the gripping member therealong. The gripping member is outwardly thrustable through the aperture in accordance with the position of the gripping member in the camming track. The inner ring includes a spacer ring, a cage ring and a rolling member. The spacer ring has the camming track and is adapted to be fitted inside the outer ring. The cage ring is rotatably mounted inside the spacer ring and is adapted to be fitted over the mandrel. The cage ring has at least one ramping track. The rolling member is fitted between the spacer ring and the cage ring to move along the ramping track. The rolling member is outwardly thrustable against the spacer ring in accordance with the position of the rolling member in the ramping track.

[0027] By employing apparatus and methods of the foregoing type, an improved technique is achieved for intermediating the force transfer from a winding mandrel to a core. In the preferred embodiment, an annular ring placed between the mandrel and core can engage both the mandrel and core to permit slipping with respect to the mandrel but not with respect to the core. Therefore one can design the inside surface of the annular device to have a well-established slipping characteristic so that the machine can be operated reliably and repeatably. Because the annular device is locked onto the core, the highly variable slip characteristics of the core do not affect machine operation.

[0028] In the preferred embodiment a pair of concentric, nested rings can rotate relatively, but only to a limited extent. Individual balls ride in a number of camming tracks that are distributed around the periphery of the inner ring. Preferably, the tracks extend in a circumferential direction and are deepest at their centers (although tracks that continually descend until reaching one end are contemplated). The balls are carried in apertures in the outer ring and therefore, when the rings relatively rotate, the balls ride the tracks and are outwardly thrust (or inwardly retract) through the apertures.

[0029] In this preferred embodiment, the mandrel is fitted with a number of pistons that are directly driven by pneumatic pressure. This arrangement avoids the complications associated with using an intermediate diaphragm or bladder. In the preferred mandrel, a predetermined number of pistons (for example three or four) radiate from a number of stations distributed along the length of the mandrel. The pistons at each station are distributed equiangularly, but the piston pattern is shifted from station to station at half the pitch at each station, in order to stagger the pistons. For example, with three or four pistons at each station, the angular spacing at each station is 60° or 45°, respectively, but the pistons pattern can be shifted 30° or 45°, respectively, from station to station.

[0030] With this arrangement, the pistons can be retracted and the annular rings placed in position over the mandrel. Cores can then be loaded over the annular devices. The outer ring can then be rotated relative to the inner ring to lock the annular devices onto the cores. Thereafter, a web can be wound onto the core is in the usual fashion. Once the cores are fully wound, the mandrel (or the cores) can be rotated in a direction to unlock the annular devices so that the cores can be removed. It is not necessary in all cases to produce that relative rotation to induce unlocking. In some instances a separate mechanism, or an axially applied force, may also induce unlocking, and which also enhances removal of the rolls.

[0031] Should the next operation involve cores having different dimensions, the annular devices can be easily replaced. The replacement annular devices can be dimensioned to accommodate various types of cores.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above brief description as well as other objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of presently preferred but nonetheless illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings, wherein:

[0033]FIG. 1 is an exploded, axonometric view of an annular device in accordance with principles of the present invention;

[0034]FIG. 2 is an end view, partially in section, of the annular device of FIG. 1 mounted on a mandrel with reciprocating pistons;

[0035]FIG. 3 is a side view of a pair of the annular devices of FIG. 1 mounted side-by-side with a thrust washer between them;

[0036]FIG. 4 is a detailed, fragmentary, cross-sectional view of a portion of the annular device of FIG. 1 in a locked condition;

[0037]FIG. 5 is a detailed, fragmentary, cross-sectional view of the annular device of FIG. 1 in an unlocked condition;

[0038]FIG. 6 is a detailed, fragmentary, side view of a portion of the inner ring of the annular device of FIG. 1; FIG. 7 is a detailed, fragmentary, side view of a portion of an inner ring that is an alternate to that of FIG. 6;

[0039]FIG. 8 is an end view, partially in section, of an annular device that is an alternate to that of FIG. 2;

[0040]FIG. 9 is a side view of the spacer ring of the annular device of FIG. 8;

[0041]FIG. 10 is a longitudinal-sectional view of the mandrel of FIG. 2; and

[0042]FIG. 11 is a side view of the mandrel of FIG. 10 fitted with the annular devices of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] Referring to FIGS. 1-6, the illustrated annular device has an inner ring 10 and an outer ring 12. Outer ring 10 has four equiangularly spaced, conically tapered apertures 14. Apertures 14 converge in an outward direction at a conical angle of 40°, although other angular dimensions can be used in alternate embodiments. In some embodiments the aperture can be formed with a bushing that establishes the dimensions and materials on the inside faces of the apertures. Also in this embodiment, outer ring 10 is 3.0 inches (7.6 cm) in diameter, ½ inch (1.3 cm) wide, and ⅛ inch (0.32 cm) thick, although other dimensions may be employed depending upon the size of the corresponding core (to be described presently) as well as the desired strength and weight for the outer ring.

[0044] As will be described presently, inner ring 10 will establish a slipping relationship with a driving mandrel. For this reason, the material of inner ring 10 is chosen to provide reliable and repeatable slipping characteristics. In a preferred embodiment, inner ring 10 is formed from a sintered metal such as brass (either all of the ring or just an inside portion). The interstices of the sintered metal are impregnated with a friction moderating substance such as oil and PTFE (polytetrafluoroethylene, known under the commercial brand TEFLON™). In some embodiments, the sintered metal impregnated with a lubricant will be an inner layer fused to the main body of the inner ring.

[0045] The periphery of inner ring 10 has four equiangularly spaced, camming tracks 16. Tracks 16 are frustro-cylindrical and make a chordal intersection with the periphery of inner ring 10. Accordingly, the floor of the tracks 16 as shown in the cross-section of FIG. 2 appear as a straight chord, so that the track depth is greatest at the center position of the tracks 16. Preferably, the camming tracks will be plated with a relatively hard material to avoid wear.

[0046] While four camming tracks are shown, in some embodiments a greater or lesser number may be used. Also, while the illustrated camming tracks are straight, in other embodiments the floor of the camming track can be graded to provide more or less leverage for the gripping actions to be described presently.

[0047] Gripping members 18 are shown herein as four balls 18 dimensioned to ride in camming tracks 16. The balls 18 are also dimensioned to fit inside the tapered apertures 14 without passing through the apertures. In this embodiment, balls 18 are ¼ inch (0.64 cm) in diameter and are made of stainless steel, although other dimensions and materials may be used in alternate embodiments. In some embodiments, the surface of the balls 18 may be roughened to enhance friction and therefore the gripping capability of the balls.

[0048] When the rings 10 and 12 are relatively rotated to the orientation shown in FIG. 5, ball 18 rests in the central position of camming track 16, which is the deepest portion of the track. Accordingly, ball 18 is not outwardly thrust and does not extend through aperture 14 to the outside of ring 12. When the rings 10 and 12 are relatively rotated as shown in FIG. 4, ball 18 rolls to one end of camming track 16, which is one of the shallowest portions of tracks 16. Accordingly, ball 18 is outwardly thrust through aperture 14 to partially extend outside ring 12.

[0049] While spherical gripping members are illustrated, in other embodiments these gripping members may be cylindrical rollers. In the latter case, the aperture through the outer ring may be a trapezoidal prism. In still other embodiments the gripping members may be sliding members having various shapes.

[0050]FIG. 6 shows camming track 16 with a circumferentially disposed, main groove 1 6A. Camming track 16 also has an egress groove 16B, which is an axially disposed, frustro-cylindrical trough transversely intercepting main groove 16A. When ball 18 is in the central or neutral unlocked position (as shown in FIG. 5) the ball can transfer to transverse groove 16B, so that the inner and the outer rings 10 and 12 can be detached from each other. Groove 16B can be made with tight tolerances so that the rings do not detach spontaneously.

[0051] In the alternate embodiment of FIG. 7, alternate ring 1 0′ has a circumferentially disposed main groove 1 6A′ intercepted with an egress groove 1 6B′, to form a camming groove 16′. In this embodiment, the deepest end of groove 16A′ is at the end adjacent egress groove 16B′. This arrangement is unidirectional in that a gripping member riding in groove 1 6A′ will always be thrust (or retracted) for a specified direction of rotation.

[0052] Referring to FIG. 2, mandrel 20 is shown as a shaft with four radially disposed channels 22 which are spaced 90° from each other, although a greater or lesser number of channels may be employed in alternate embodiments. In a constructed embodiment, the channels were spaced 120°. In the illustrated embodiment, mandrel 20 is {fraction (2 1/4)} inches (5.7 cm) in diameter, although other embodiments will employ different mandrel sizes.

[0053] The proximal ends of channels 22 merge into a central fluid passage 24, so that all channels can be simultaneously pressurized. Channels 22 are cylindrical and contain cylindrical pistons 26. Pistons 26 have a frustro-conical proximal end and a distal end rounded cylindrically to match the cylindrical outside surface of mandrel 20. Pistons 26 have an outside diameter of ½ inch (1.3 cm) although other piston sizes are contemplated. Pistons 26 each have an annular groove holding an annular seal 28. Seal 28 is an annular, channel-shaped member (U-shaped cross-section), also known as a U-cup seal. With this arrangement a pressure applied to fluid passage 24 communicates with each of the channels 22 to drive the pistons 26 outwardly. Also, while pistons directly actuated by pneumatic pressure are shown, in some embodiments a central bladder may press against moving members to provide the same action as it is provided by the pistons.

[0054] Referring to FIGS. 2 and 3, rings 10 and 12 can be rotated to the position shown in FIG. 2 to thrust outwardly gripping members 18. As shown in FIG. 3 gripping members 18 are thrust against the inside surface of cores 30. As a result, outer rings 12 can be positively locked onto cores 30. Therefore, web 32 can be wound onto the cores 30 by rotating rings 12.

[0055] In most instances, adjacent cores will not be wound side-by-side on a mandrel so as to avoid interference. Instead, cores will be installed on every other device 10/12. Because the cores 30 are locked in place by gripping members 18, there is no need for spacers to keep the cores 30 centered on annular devices 10/12. In some instances, the cores may be relatively wide and may lock onto more than one of the annular devices 10/12. In some cases, the width of the cores may not be a simple multiple of the annular devices 10/12 but may span, for example, {fraction (2 1/2)} devices.

[0056] Regardless, in some cases cores may alternate with spacers to positively establish a gap between webs to avoid interference. Alternatively, the illustrated annular devices composed of rings 10 and 12 may alternate with simple spacers having a greater outside diameter than the outer ring 12 in order to keep cores 30 centered on the annular devices 10/12.

[0057] A thrust washer 34 is located on either side of each annular device 10/12. This washer is preferably a disk made of plastic or TEFLON™. This washer facilitates situations where an adjacent annular device does not have a core and therefore will tend to run at the same speed as the mandrel, that is, without slipping. This requires relative rotation between adjacent annular devices 10/1 2 and the thrust washers 34 provides lubrication between adjacent devices. In other embodiments suitable coatings could be applied to the adjacent surfaces to eliminate the need for such washers.

[0058] Referring to FIG. 10, fluid passage 24 is shown running substantially the length of previously mentioned mandrel 20 to communicate with previously mentioned channels 22. Channels 22 form repetitive bands, each having four channels located at discrete stations, although some embodiments will have fewer or more channels depending on the system requirements. Each of the bands of channels 22 are interleaved with bands of channels 22′. Channels 22′ are identical to channels 22 but are angularly displaced by 45° (four channel embodiment). For embodiments having three channels per band (120°0 spacing), the channel pattern will be displaced by 60° from band to band. Therefore the bands composed of channels 22 and 22′ form a plurality of axially equidistant bands.

[0059] The driven (left) end of mandrel 20 has a reduced diameter and has bolted to it a collar 36 whose proximal end includes a flange 38 for attaching the mandrel to a complementary driving flange (not shown). Inlet 40 of mandrel 20 connects to a rotary union (not shown) to provide pneumatic pressure to the mandrel.

[0060] Referring to FIG. 11, previously mentioned mandrel 20 is shown fitted with a number of annular devices 10/12, which are held on the left by collar 36. On the right, annular devices 10/12 are held by cap 42, which is bolted on the distal end 20A of the mandrel 20. A pair of bearings 44 and 46 are mounted on the tip of the distal end 20A of mandrel 20. Bearing 44 is shown mounted on structure or 48 to support one end of the mandrel under ordinary operating conditions. The second bearing 46 can rest in a pocket formed in lifting device 50, which can be used to lift mandrel 20. Such lifting may be useful in order to quickly load or unload cores 30 that have been wound with webs.

[0061] Referring to FIGS. 8 and 9, previously mentioned mandrel 20 is shown fitted with an alternate annular device. Components in this annular device corresponding to those shown in FIG. 2 have the same reference numeral, but increased by 100. A relatively larger outer ring 112 is fitted with eight gripping members 118, shown as nylon balls. In this embodiment outer ring 112 is ⅛ inch thick (0.32 cm), 1.0 inch (2.5 cm) wide, and has an outside diameter of 6.0 inches (15.2 cm). Eight balls 118 are fitted in apertures 114, which are distributed equiangularly around the periphery of outer ring 112. Balls 118 are in this embodiment ¼ inch (0.64 cm) in diameter.

[0062] An inner ring is formed herein by an aluminum spacer ring 110A encircling cage ring 110B, the latter being formed from the previously mentioned, friction moderating material; namely, sintered brass impregnated with oil and PTFE. Formed in the periphery of spacer ring 110A are a number of camming tracks 116 and 116′. Tracks 116 are contained in one band, while tracks 116′ are contained in another axially spaced band. As before, camming tracks 116 each comprise a circumferentially disposed, main groove 116A and a transverse egress groove 116B. Camming tracks 116′ each also comprise circumferentially disposed, main groove 116A and transverse egress groove 116B, but egress groove 116B′ is substantially longer to accommodate the axial displacement of this band of tracks 116′. The camming tracks 116 are separated by a predetermined angle of 90°. The camming tracks 11 6′ are also separated by a predetermined angle of 90°. Camming tracks in adjacent bands have a minimum angular separation of half said predetermined angle, or 45 °. For embodiments having an angular separation of 120° in each band, the minimum angular separation between bands of 60°.

[0063] Cage ring 110B is in this embodiment ¼ inch (0.64 cm) thick and has four ramping tracks 152. These tracks are identical to tracks 116 and 116′, except for being half in number. Accordingly, tracks 152 have egress tracks 158. A rolling member in the form of a nylon ball 1 54 is shown in track 152.

[0064] Ball 154 is also showing extending into conical cavity 156. With this arrangement, relative rotation of rings 110A and 110B causes ball 154 to roll from the central position to the shallowest part of track 152, causing ball 154 to be outwardly thrust and locked into the conical sides of cavity 156. This locks together rings 110A and 110B.

[0065] In some embodiments such a double locking mechanism will not be used and instead, ring 110B will be press fit into ring 110A. Also, while the embodiment of FIGS. 8 and 9 are shown achieving a larger working diameter with a smaller mandrel, it is anticipated that in most instances a larger working diameter will be achieved by replacing the smaller mandrel with a larger mandrel. Using a larger mandrel will increase the overall strength of the arrangement.

[0066] To facilitate an understanding of the principles associated with the foregoing apparatus, its operation will be briefly described. Initially, mandrel 20 may be located at a workstation near the winding machine in order to load the mandrel. Alternatively, the distal end 20A of mandrel 22 may be lifted by carrier 50 after it engages bearing 46. Once lifted in this fashion, supplies previously loaded onto carrier 50 can then be slid onto mandrel 20. In still other embodiments the distal end 20A may be left unsupported or cantilevered as the mandrel 20 is loaded.

[0067] In any event, no pressure will be applied through fluid passage 24 and therefore pistons 26 (FIG. 2) will be in a retracted position. Accordingly, inner ring 10 together with outer ring 12 can be fitted over mandrel 20. As shown in FIG. 11 the annular devices 10/12 can be stacked side-by-side on mandrel 20 with thrust washers 34 in between each device (FIG. 3).

[0068] Outer rings 12 are then rotated to bring ball 18 to the central position in camming tracks 16 as shown in FIG. 5. Balls 18 are then retracted so that cores 30 (FIG. 11) can be fitted over annular devices 10/12. Mandrel 20 can then be installed into its normal operating position in the winding machine.

[0069] Often a relatively wide web will be slit into a number of thinner webs by an upstream sheet slitter. These thinner webs can be separated by grouping alternate slit webs so that adjacent webs are routed onto different paths. For this reason, mandrel 20 in FIG. 11 shows cores 30 on alternate ones of the annular devices 10/12. This resumes that another complementary mandrel will take up the other alternate thin webs.

[0070] Next, the outer rings 12 are rotated (relative to the inner ring 10) in the reverse of the winding direction, typically by rotating cores 30 and relying on the friction between the cores and the outer rings. This rotation drives gripping members 18 to the shallow end of camming tracks 16, so that members 18 are thrust outwardly beyond the perimeter of outer rings 1 2. Consequently, gripping members 18 lock onto the inside surface of the cores 30.

[0071] Thereafter, pressure applied through fluid passage 24 to the proximal end of pistons 26 in channels 22 outwardly drives the pistons 26 against the inside surface of inner rings 10 to hold them in place. In contrast to a relatively inefficient, bladder type of design, the increase of the fluid volume inside the mandrel need only increase by the amount needed to displace pistons 26. Webs 32 (FIG. 3) can now be secured to core 30 by tape or other means. The mandrel 20 is then rotated in the winding direction to wind webs 32 onto core 30.

[0072] The pressure in passage 24 is regulated to apply a desired frictional force between pistons 26 and inner ring 10. In particular, a certain amount of slipping is allowed between pistons 26 and inner ring 10. Because inner ring 10 is impregnated with a lubricant, slipping is facilitated without a high degree of wear and heat. Also, the interface between pistons 26 and inner ring 10 is highly consistent and is under control of the designer; in comparison with an interface with a core that may be made of different materials exhibiting different slipping characteristics.

[0073] This slipping moderates the torque applied by mandrel 20 and therefore the tension on web 32. Also, by adjusting the pistons this frictional force and slippage can be adjusted during the winding phase to account for the increasing diameter of the wound package and also to adjust the desired tension profile across the package. Also, unlike bladder-type designs that introduce nonlinearities, directly applying pressure to the pistons allows a much more accurate control of the output torque at the produced by the pistons. Regardless, in some situations pistons 26 may be driven against inner ring 10 with such force that no slipping is permitted.

[0074] After the web 32 has been fully wound onto core 30, the mandrel 20 is decelerated and stopped. The tail of web 32 may be cut, if necessary, and secured by tape or otherwise to the wound package. Thereafter core 30 can be rotated in the winding direction to cause ball 18 to move from the position shown in FIG. 4 to that shown in FIG. 5. Ball 18 can then retract in aperture 14 to the deepest portion of tracks 16 in order to release core 30. Core 30 and the wound packages can then be removed from mandrel 20 in various ways. For example, mandrel 20 can be removed from the winding machine. Alternatively the mandrel end 20A can be lifted by carrier 50, in order to remove the wound package on cores 30.

[0075] The annular devices 10/12 can also be removed at this time and replaced with devices having a different width and diameter. For example, the annular device of FIG. 8 can be placed over mandrel 20 as shown. Thereafter, assuming ring 110B is fixed, ring 110A is rotated in the reverse of the winding direction to drive ball 154 to a shallow end of track 152 in order to lock rings 110A and 110B together.

[0076] After cores are placed around outer ring 112, rings 112 (relative to ring 110A) are rotated in the reverse of the winding direction to drive balls 118 to a shallow end of tracks 116 and 116′. This procedure locks the cores to the annular device. Thereafter the process precedes in the same fashion as was described previously in connection with the embodiment of FIG. 2.

[0077] Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. 

1. An annular device for intermediating force transfer between a winding mandrel and a core onto which a web is to be wound, comprising: an outer ring having at least one aperture and adapted to be fitted inside said core; an inner ring rotatably mounted inside said outer ring and being adapted to be fitted over said mandrel, said inner ring having at least one camming track, said inner ring having an inside portion comprising a material different from material of said outer ring; and a gripping member fitted in said aperture of said outer ring to move along said camming track, said gripping member being outwardly thrustable through said aperture in accordance with the position of said gripping member in said camming track.
 2. An annular device according to claim 1 wherein said inner ring has an inside surface impregnated with a friction moderating substance.
 3. An annular device according to claim 1 wherein said inner ring has an inside portion comprising a sintered material impregnated with a friction moderating substance.
 4. An annular device according to claim 1 wherein said gripping member has a surface roughened to enhance its gripping ability.
 5. An annular device according to claim 1 wherein said gripping member is shaped to roll in said camming track.
 6. An annular device according to claim 5 wherein said gripping member is spherical.
 7. An annular device according to claim 1 wherein said camming track has a central position and is shaped to increasingly thrust said gripping member outwardly as it moves away from said central position.
 8. An annular device according to claim 1 wherein said camming track has a depth that varies over its length.
 9. An annular device according to claim 8 wherein said camming track substantially extends circumferentially.
 10. An annular device according to claim 8 wherein said camming track is deepest substantially at its center.
 11. An annular device according to claim 8 wherein said camming track has a pair of ends and is deepest substantially at one of its ends.
 12. An annular device according to claim 1 wherein said at least one camming track comprises a spaced plurality of camming tracks, circumferentially successive ones of said camming tracks being spaced axially.
 13. An annular device according to claim 12 wherein said plurality of camming tracks are grouped into a plurality of axially spaced bands.
 14. An annular device according to claim 13 wherein camming tracks within each band are equiangularly spaced by a predetermined angle, camming tracks in adjacent bands having a minimum angular separation of half said predetermined angle.
 15. An annular device according to claim 1 wherein said aperture in said outer ring is tapered.
 16. An annular device according to claim 15 wherein said gripping member is spherical and said aperture is conically tapered.
 17. An annular device according to claim 1 wherein said camming track has a circumferentially disposed, main groove and an egress groove transversely intersecting said main groove, said egress groove being sized to permit escape of said gripping member in order to disengage said inner and said outer ring.
 18. An annular device according to claim 1 wherein said inner ring comprises: a spacer ring having said camming track and adapted to be fitted inside said outer ring; a cage ring rotatably mounted inside said spacer ring and being adapted to be fitted over said mandrel, said cage ring having at least one ramping track; and a rolling member fitted between said spacer ring and said cage ring to move along said ramping track, said rolling member being outwardly thrustable against said spacer ring in accordance with the position of said rolling member in said ramping track.
 19. An annular device according to claim 1 further comprising: a thrust washer mounted coaxially to one side of said outer and said inner ring.
 20. A web winding assembly for engaging and disengaging cores with a plurality of annular devices mounted thereon, comprising: a mandrel having a spaced plurality of radially disposed channels, said mandrel having a fluid passage communicating with said channels; and a plurality of pistons mounted to reciprocate in different corresponding ones of said channels, said pistons being operable in response to fluid pressure in said channels to extend out of said mandrel in order to bear on said annular devices, changes in the volume of fluid inside said fluid passage and said channels being substantially equal to the total displacement of the pistons.
 21. A web winding assembly according to claim 20 wherein some of said channels are axially spaced.
 22. A web winding assembly according to claim 20 wherein said plurality of channels are grouped into a plurality of axially equidistant bands, channels within each band being equiangularly spaced by a predetermined angle, channels in adjacent bands having a minimum, band-to-band, angular separation of half said predetermined angle.
 23. A web winding assembly according to claim 20 wherein said fluid passage is centrally disposed to extend longitudinally within said mandrel.
 24. A web winding assembly according to claim 20 wherein said pistons each comprise an encircling annular seal.
 25. A web winding assembly according to claim 20 comprising a plurality of annular devices mounted side by side around said mandrel for intermediating force transfer between the mandrel and a core onto which a web is to be wound.
 26. A web winding assembly according to claim 25 wherein said annular devices each comprise: an outer ring having at least one aperture and adapted to be fitted inside said core; an inner ring rotatably mounted inside said outer ring and being adapted to be fitted over said mandrel, said inner ring having at least one camming track; and a gripping member fitted in said aperture of said outer ring to move along said camming track, said gripping member being outwardly thrustable through said aperture in accordance with the position of said gripping member in said camming track.
 27. An annular device according to claim 26 wherein said inner ring has an inside portion comprising a material different from material of said outer ring.
 28. An annular device according to claim 26 wherein said inner ring has an inside surface impregnated with a friction moderating substance.
 29. An annular device according to claim 26 wherein said gripping member is shaped to roll in said camming track.
 30. An annular device according to claim 26 wherein said gripping member has a surface roughened to enhance its gripping ability.
 31. An annular device according to claim 26 wherein said camming track has a central position and is shaped to increasingly thrust said gripping member outwardly as it moves away from said central position.
 32. An annular device according to claim 31 wherein said camming track is deepest substantially at its center.
 33. An annular device according to claim 26 wherein said aperture in said outer ring is tapered.
 34. An annular device according to claim 25 further comprising: a plurality of spaced thrust washers mounted coaxially between said annular devices.
 35. A web winding method employing annular devices located on a mandrel fitted with core engaging pistons, comprising the steps of: loading said cores over said annular devices; outwardly driving said pistons with directly applied fluid pressure in order to frictionally engage said annular devices with said pistons, changes in the volume of fluid inside said mandrel being substantially equal to the total displacement of the pistons; locking said cores onto said annular devices; rotating said mandrel to wind the web while allowing slippage predominantly between said annular device and said mandrel, in order to avoid slippage predominantly influenced by interface attributes between said cores and said annular devices; and unlocking and removing said cores from said annular devices.
 36. A method according to claim 35 wherein said annular devices are operable to lock onto said cores in response to relative rotation between said mandrel and said cores in a first direction, the step of locking the cores to the annular devices comprising the step of: causing relative rotation between the mandrel and the cores in a first direction.
 37. A method according to claim 36 wherein said annular devices are operable to unlock from said cores in response to relative rotation between said mandrel and said cores in a direction opposite to said first direction, the step of unlocking the cores from the annular devices comprising the step of: causing relative rotation between the mandrel and the cores in a direction opposite to said first direction.
 38. A method according to claim 35 comprising the steps of: replacing the annular devices with differently sized annular devices after removing the cores; and loading differently sized, fresh cores onto the differently sized annular devices.
 39. A method according to claim 35 wherein said annular devices each have an inner and an outer ring that can be relatively rotated to lock onto and unlock from said cores, the step of locking the cores to the annular devices comprising the step of: causing relative rotation between the inner and the outer ring in a first direction.
 40. A method according to claim 39 wherein the step of unlocking the cores from the annular devices comprise the step of: causing relative rotation between the inner and the outer ring in a direction opposite said first direction.
 41. A method according to claim 35 wherein said annular devices each have an inner and an outer ring that can be relatively rotated from a neutral unlocked position in either direction to lock onto said cores, the step of locking the cores to the annular devices comprising the step of: causing relative rotation between the inner and the outer ring in a first direction from said neutral position.
 42. A method according to claim 41 wherein the step of unlocking the cores to the annular devices comprising the step of: causing relative rotation between the inner and the outer ring in a direction opposite the first direction toward said neutral position.
 43. An annular device for intermediating force transfer between a winding mandrel and a core onto which a web is to be wound, comprising: an outer ring having at least one aperture and adapted to be fitted inside said core; a gripping member fitted in said aperture of said outer ring, an inner ring rotatably mounted inside said outer ring and being adapted to be fitted over said mandrel, said inner ring having at least one camming track for receiving and allowing movement of said gripping member therealong, said gripping member being outwardly thrustable through said aperture in accordance with the position of said gripping member in said camming track, said inner ring including: (a) a spacer ring having said camming track and adapted to be fitted inside said outer ring; (b) a cage ring rotatably mounted inside said spacer ring and being adapted to be fitted over said mandrel, said cage ring having at least one ramping track; and (c) a rolling member fitted between said spacer ring and said cage ring to move along said ramping track, said rolling member being outwardly thrustable against said spacer ring in accordance with the position of said rolling member in said ramping track. 